//Write a program to accept a number and check it is a Keith number or not.
//A Keith number is an integer n with d digits with the following property. if a fibonacci like sequence
//is formed with the first d terms. ex- 197 is a keith number
//1,9,7,17,33,57,107,197
import java.util.*;
class keith1
{
public static void main(String[]args)
{
Scanner sc=new Scanner(System.in);
System.out.println("Enter a no");
int n=sc.nextInt();//197
int c=0,k=n,k1=n,s=0,sum=0,r=0,s1=n%10,num=n;//variable c to count the digit,k,k1,num to store the number,s,sum to store the sum,r to store the result,s1 to store the last digit
while(n>0)
{
c=c+1;//3
s=s+(n%10);//17
n=n/10;
}
int s2=s,c1=c;//variable s2 to store the sum,c1 to store the no of digits
while(c>0)//3>0 t//2>0 t//1>0 t//0>0 f
{
sum=sum+s;//0+17=17//17+16=33//33+24=57
r=k/(int)Math.pow(10,c-1);//197/100=1//97/10=9//7/1=7
s=sum-r;//17-1=16//33-9=24//57-7=50
k=k%(int)Math.pow(10,c-1);//197%100=97//97%10=7//7%1=0
c--;
}
if(sum==k1)//50==197 f
System.out.println("It is a keith no");
else
{
while(sum<=k1)//50<=197//93<=197//169<=197
{
sum=(2*sum)-s1;//2x50-7=93//2x93-17=169//2x169-33=305
s1=s2;//17//33//
if(c1>0)//3>0 t//2>0 t
{
s2=s2+(s2-(num/(int)Math.pow(10,c1-1)));//17+(17-197/100)=33//33+(33-97/10)=57
num=num%(int)Math.pow(10,c1-1);//197%100=97//97%10=7
}
c1--;
if(sum==k1)
break;
}
if(sum==k1)
System.out.println("It is a keith no");
else
System.out.println("It is not a keith no");
}
}//main method opens
}//class opens
